From what I remember form high school chemistry and physics, it's very rare for any form of combustion to be complete -- especially in situations where there are large fans present like inside a jet engine. The small percentage of the (vast quantity of) fuel that is not burned will pass out with the exhaust gasses, leaving an effect similar to a crop duster at 40000ft.

No big deal, it's biodegradable, and will be spread over a very large area at low concentrations, it's never been a problem with conventional jet fuel... No big deal until someone says the phrase nut allergy...

Does this mean that people will be dropping down dead from nut alergies everywhere?

From what I've read, the jatropha is fine in otherwise poor land, but to provide a good crop of nuts requires good soil and plenty of water, both of which would seem to make it as bad a choice as corn or other fuel crops.

well, most "nut" allergies are attributed to Peanuts, which acually belong to the pea family, rather than then nut family.

so if my dark distant remembering of vegetable genus is correct, we should be ok on this one... :)

my only thought is, how many nuts must you squeeze to part fuel mix a jet engine?

plus an engine designed to burn mixed fuels will get better power/efficiency, than a parafin burning turbine. hell it could burn vodka..... stopping off at duty free to fill up just took another meaning...